TRIBE MYTILACEA. 241 



M. Striatula. Nobis Zool. Proc. 1844. Elongated-oblong, 

 narrow, subarcuated, subcylindraceous, covered with an olive epi- 

 dermis which is usually rayed anteriorly with narrow black streaks ; 

 posterior side short, with three or four rather distant radiating ribs; 

 anterior side produced and rayed with most delicate striae, which at 

 their extremity become slightly elevated and divaricate ; interme- 

 diate space smooth ; dorsal margin scarcely elevated and very 

 slightly convex, forming a very indistinct angle with the convex 

 anterior which is nearly equal to it in length ; umbones depressed ; 

 within purple, hinge crenated at the end of the ligament. Philippines 



3_ 1 2. 



i o • • x 5 ' 



M. Subramosa Nobis Zool. P 1844. Elongated oblong, narrow, 

 moderately ventricose, covered anteriorly with forked and subra- 

 mose rather large and moderately distant depressed ribs, which on 

 passing the very distinct (and in the young subcarinated) umbonal 

 ridge, become fine strice, disappear and leave the posterior ventral 

 side smooth ; hinge margin very short (crenated at its extremities 

 within) forming a distinct but little elevated angle with the anterior 

 which is first incurved, nearly parallel with the ventral, and then 

 slopes suddenly in a convex line to the incurved ventral, causing 

 the compressed and produced anterior extremity to appear obtusely 

 biangulated ; beaks narrow, incurved, all but terminal ; within, tin- 

 ged anteriorly with purple, i . . 1 1. — Mindinao. 



Section E. 

 With radiating strice. No dorsal angle. 



M. Impacta. — Herman Naturf. 17. t. 3. f. 5 to 8. — D. p. 320. 

 W. t. 12. /. 40.— Myt. Australis. Fabr. in Dankse V. S. S. 3. 

 (1778)— Ch. f. 768.— Myt. Cor. Marty n U. C. t. 77.— (Born, 

 vignette p. 121. D.J Modiola Discors. Lam. 16. — E. t. 204./. 5. 

 Oval, ventricose, under an yellowish olive cuticle of a reddish ash 

 colour, a few distant rounded raised]longitudinal sulci at the posterior 

 end, and numerous grooves and very depressed costellae anteriorly ; 

 intermediate area glabrous and very convex, with the ventral edge 

 swelling out there; umbones tumid, lj — S. Seas. 



M. Tumida.* — M. Discors Macgyl. Ab. p. 239. — Turt. B'»v. t. 

 15. /. 4, 5. — Mytilus Discors Mont. p. 167. — D. p. 319. — W. t. 

 12./. 39.— Turt. C. D.p. 112.— Da. Cos. t. 17. / l.—Poli. t. 13. 

 /. 15. — Mod. Discrepans. Lam. 15. — Phil. p. 70 (from his own 

 specimen, certo) The same general appearance as the last, but the 

 epidermis light green, the posterior sulci numerous close and little 

 raised, and the umbonal ridge more elevated. 4. — England. 



M. Discors. Sow. G.—Re<ve Syst. t. 100. / 4.— Mytilus. D. 

 Lin. Sys. Ed. 12. p. 1159.— Fabr. Faur. Grcenl.—Ch.f. 764. a. b. 

 — Myt. D. var Arctica. Otho Fabr. Dankse V. S. Skriv. 3. t. S.f. 1, 

 4, 6. — M. Laevigata Gray in Sup. to Parry — W. S. t. 2. /. 5. 



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